What compromise established a permanent boundary between free and slave states in 1812

The Missouri Compromise was the legislation that provided for the admission of Maine to the United States as a free state along with Missouri as a slave state, thus maintaining the balance of power between North and South in the United States Senate. As part of the compromise, slavery was prohibited north of the 36°30′ parallel, excluding Missouri. The 16th United States Congress passed the legislation on March 3, 1820, and President James Monroe signed it on March 6, 1820.